Every month, Global Healthcare Resource's General Manager of Coding Quality, Viba Raghavendran (CPC) and Deputy General Manager of Coding Operations Sivashankari Thangavelu (CPC,BCHHC,RCC & CCS) share helpful rule reminders and coding information for specific medical conditions. In honor of National Kidney Month, our experts dive into Chronic Kidney Disease as it relates to hypertension, diabetes, anemia and transplants.
Chronic Kidney Disease
Chronic Kidney Disease (CKD) has numerous causes with hypertension (HTN) being one of the most common. Diagnosing CKD involves identifying an individual’s glomerular filtration rate (GFR) which is a measure of their kidney function levels. These levels are defined as stages 1 through 5, increasing with severity (stage 5 = kidney failure).
Coding the Stages of CKD
The ICD-10-CM code is assigned to depict the documented severity (stage) of CKD:
- N18 Chronic Kidney Disease
- N18.1 Chronic kidney disease, stage 1
- N18.2 Chronic kidney disease, stage 2 (mild)
- N18.3 Chronic kidney disease, stage 3 (moderate)
- N18.4 Chronic kidney disease, stage 4 (severe)
- N18.5 Chronic kidney disease, stage 5
- Code N18.6 End stage renal disease is assigned only when the provider has documented end-stage renal disease (ESRD).
- Encounters where both a stage of CKD and ESRD are documented, report N18.6, only.
- N18.9 Chronic kidney disease, unspecified
Coding Cause-and-Effect Relationships: CKD and Hypertension
ICD-10-CM Coding Guidance:
The ICD-10-CM code book does not have a hypertension table in the index. One reason is the reference to terms malignant and benign hypertension were removed as they were considered outdated. All three previous designations in ICD-9 are now reported with just one ICD-10 code for essential hypertension, code I10.
According to the ICD-10-CM Official Coding Guidelines (as of October 1, 2016), “The classification presumes a causal relationship between hypertension and heart involvement and between hypertension and kidney involvement…these conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.”
Category I12 (hypertensive CKD) applies when both HTN and CKD are stated as diagnoses. If the documentation specifically identifies a different cause, CKD should not be coded as hypertensive.
Hypertensive heart and CKD
Combination category I13 (hypertensive heart and CKD) applies when both hypertensive heart disease and hypertensive kidney disease are stated as diagnoses.
Category I13 includes the conditions from I11 and I12 categories. If a patient has hypertension, heart disease and CKD, only a code from I13 should be used. Do not use individual codes for hypertension, heart disease and CKD, or codes from I11 or I12.
CKD and Diabetes Mellitus
In ICD-10-CM, more than one code is required for patients with diabetic CKD. A combination code indicating the type of diabetes with diabetic CKD, along with a code identifying the stage of CKD.
Based on the type of diabetes, a code would be assigned:
- For category N18, CKD, there is an instructional note to code first any associated diabetic CKD (E08.22, E09.22, E10.22, E11.22, E13.22). Category N18 would be reported after the diabetes code, as secondary, to specify the stage of CKD (N18.1-N18.6, N18.9).
- It is also advised to use an additional code to identify dialysis status (Z99.2), if applicable. Code N18.6, end-stage renal disease, is to be reported for CKD that requires chronic dialysis.
- In ICD-10-CM, there is an assumed cause and effect relationship between diabetes and CKD when both conditions are documented in the medical record. However, if documentation specifies that diabetes is not the underlying cause of CKD, it should not be coded as a diabetic complication.
Anemia in CKD
Code D63.1, Anemia in CKD, is a manifestation code (i.e., not to be reported as a primary/ first listed diagnosis). It is necessary to first identify the underlying stage of CKD from category N18.
CKD and Kidney Transplant
Patients with a kidney transplant may still suffer some type of CKD as the transplant may not completely reinstate kidney function. Thus, having CKD alone does not mean that there is a transplant complication. Assign a code to establish the stage of CKD (N18 category) and kidney transplant status (Z94.0).
If a complication resulting from the transplant (e.g., failure or rejection) is clearly documented, it would be appropriate to code the complication of kidney transplant from subcategory T86.1-.
Like all medical conditions, Chronic Kidney Disease can be nuanced and challenging to code. We hope our monthly Coding Spotlights provide helpful rule reminders for CPCs, as well as introduce non-coding professionals to this fascinating medical language that our industry relies on every day.